The invention relates generally to an apparatus and method for performing diagnostic procedures in a body. In particular, the invention relates to a diagnostic module attachable to the distal end of an interventional device for performing endofluorescence imaging of tissue in a body.
Fluorescence-enhanced endoscopic examination of tissue typically involves an endoscope having a light source (e.g., a laser) and imaging sensors, which include filters that pass specific wavelengths associated with displasia or cancerous tissue. First, an operator obtains a white light image to locate a general area of tissue to be examined. Next, the operator actuates a second light source to illuminate the tissue with light having the appropriate wavelength(s) to produce a desired fluorescent emission from the tissue. Such endoscopes are necessarily more complex and costly than conventional endoscopes in that they require additional light sources, external control electronics and display systems, and light guides capable of transmitting ultraviolet (UV) wavelengths that are often important for fluorescence tissue spectroscopy purposes. Also, such endoscopes are inherently costly and must be carefully recycled and cleaned after each use. Recycling places a burden upon hospitals to maintain multiple endoscopes so that at least one of the various styles, lengths and types can be available for use at a given time.
It is therefore a principle object of the invention to provide a means for modifying a conventional endoscope so that it can be used to perform tissue spectroscopy. It is another object of the invention to provide a reversible means for modifying the endoscope so that it can be easily restored to its normal configuration without damage or the need for adjustments. It is yet another object of the invention to provide an attachment that can be attached immediately prior to use of such endoscope so that the user would have no need to prepare, expend or contaminate endoscopic equipment needlessly. It is yet another object of the invention to provide a low cost attachment that can be used with a wide variety of endoscopes and can modify input and output light from/to the endoscope so that fluorescence images can be produced easily, quickly and inexpensively.
An endofluorescence imaging module has been developed which is useful with a variety of interventional devices including, without limitation, endoscopes and cystoscopes. The module includes a housing which can be attached to the distal end of the interventional device. One or more light sources are disposed in the housing for illuminating tissue within the body. A light modulator is disposed in the housing for modifying the light emitted by at least one of the light sources.
In one embodiment, the housing includes an optically transparent region to pass the light originating from the light sources and received from the tissue. Light sources can include, without limitation, light emitting diodes, lasers, pulsed light sources, sources of ultraviolet energy, or a flashlamp.
The light modulator can include a filter providing a range of wavelengths to the optical channel of the interventional device. The filter can be an acousto-optic tunable filter, interference filter, grating, prism, holographic filter, or other component that provides a spectral passband. The light modulator also includes a shutter, which can be a liquid crystal device. In another embodiment, the light signal can be controlled by a signal corresponding to the operation of the flashlamp. In another embodiment, a control unit attaches to the proximal end of the interventional device. The control unit provides electrical power and control signals for operation of the light sources and detector in the module.
The invention also features a method for performing endofluorescence imaging of tissue in a body. The method includes attaching a housing having at least one light source and a light modulator to the distal end of an endoscope. The method further includes illuminating the tissue using at least one of the light sources. In one embodiment, the method includes transmitting pulses of optical energy. In another embodiment, the method includes controlling the exposure of the optical channel of the endoscope. In another embodiment, the method includes spectrally filtering the optical energy from the tissue. In another embodiment, the method further comprises the steps of providing a control unit having a power supply and control electronics; attaching the control unit to the proximal end of an endoscope; and providing electrical power and control signals to the light source and detector.